NVIDIA GeForce GTS 250 vs GTS 450 DDR3

Since two cards have the same number of ROPs and the NVIDIA GeForce GTS 450 DDR3 has higher operating frequency, its pixel fillrate is higher. Better pixel fill rate allows more pixels to be drawn on screen per second, which results in increased GPU performance, unless the card is limited by something else, such as memory bandwidth or texture mapping.

Even though it has lower graphics frequency, the GeForce GTS 250 comes with twice as many TMUs, which results in substantially higher texture fill rate. Better texture fill rate means that the GPU can use more sophisticated 3D effects and/or map more textures to each textured picture element, which improves visual appearance of games and generated images.

Single Precision performance is convenient for estimating card's maximum speed in programs, that process mainly single-precision floating point data. The performance is expressed in GFLOPS, which stands for Giga (billions of) Floating Point Operations Per Second. All single-precision calculations are performed by stream processors or CUDA cores, thus the more cores / processors the graphics unit has the better. Performance also depends on the processor clock rate. The GeForce GTS 450 DDR3 is faster here. Higher single-precision performance number means the graphics card will perform better in general computing applications. Since CUDA cores or stream processors are also used as vertex and geometry shaders for 3D image generation, higher performance is also beneficial to games.

To speed up processing, the graphics cards store 3D scene data, textures and intermediate data, used for image generation, in on-board memory. The video memory usually has much higher bandwidth than system RAM, and more bandwidth allows the graphics card to run at higher display resolutions, use larger and more detailed textures, and apply more complex 3D effects and filters. The bandwidth is dependent on memory type, speed, and width of memory interface. In this case, the NVIDIA GeForce GTS 250 offers higher memory clock and wider bus. As a result, it has considerably higher memory bandwidth.